Recently, various electronic products such as a digital telephone, a camera, an electronic notebook, a Personal Digital Assistant (PDA), a smart phone, a media player, a notebook computer, a tablet PC, an all-in-one PC, a monitor and a T.V. are being developed and propagated. Many of these electronic products have a construction that receives external commercial AC power using a power adaptor. According to a trend in which a power adaptor is externally separated and is used in order to make an electronic product to be thin, it is expected that the use of the power adaptor will be increased in the future.
For example, a power adaptor that includes a power plug, one that is connected to a wall socket (or a wall outlet) to receive commercial AC power of 220 V, generates DC operation power of a corresponding electronic product that is connected to the power adaptor, and outputs the DC operation power such as 15 V.
For example, the technology related to an electronic product which receives power using such a power adaptor is disclosed in a domestic patent application No. 10-2003-84343 (title: “power supply control method, current-to-voltage conversion circuit and electronic apparatus,” applicant: FUJITSU LIMITED, inventor: Shigeo Tanaka et al. one person, application date: 2003 Nov. 26) and a domestic patent application No. 10-2010-7015780 (title: power adaptor”, applicant: Sony Ericsson Mobile Communications AB, inventor: Fredrik Bagenholm et al. one person, application date: 2008 Sep. 2).
Meanwhile, recently, standby power cutoff devices of various structures have been employed in an electronic product. In the electronic product using the power adaptor as described above, cutting off the standby power of the power adaptor is not easy. That is, even though the power of the electronic product is turned off or the electronic product is separated from the power adaptor, if a power plug of the power adaptor is not separated from a wall socket (or a wall outlet), the power of the power adaptor is not cut off. In this case, since the standby power of the power adaptor is generated, power is unnecessarily dissipated, and when the power adaptor is struck by lightning, the product is damaged, since power is continuously provided, a lifetime of the product is shortened, and when the product is shorted, there is risk of fire due to an over-current.